1. Field of the Invention
The present invention relates to a battery pack and an electrical/electronic device, and particularly to a battery pack having a charge request function and a charge-stop request function, and an electrical/electronic device having a function for charging an installed battery pack.
2. Description of the Prior Art
In recent years, portable computers such as a personal computer of a notebook type, which is formed into a small-sized and lightweight device in consideration of portability; have become widespread. Most of these kinds of portable computers enable installation of a packaged battery (hereinafter referred to as a battery pack) in the portable computer such that the portable computer can operate even in a place where a public-supplied power source is not available. A battery pack installed in this type of portable computer can be charged while the portable computer is connected to a public-supplied power source or the like such that electric power from the public-supplied power source is being supplied to the battery pack via an AC/DC adapter or the like.
This charging for a battery pack is controlled by a charge controller provided within the portable computer. The charge controller accumulates a discharge current of the battery pack. When it is determined that the remaining capacity of the battery pack is at or below a predetermined value, the charge controller starts charging the battery pack. Further, during charging the charge controller accumulates a charging current for the battery pack. When it is determined that the battery pack is brought into a full-charged state, the charge controller stops charging the battery pack. The charged battery pack supplies electric power for the main body of the portable computer when the portable computer is disconnected from a public-supplied power source or the like.
Further, in relation to the foregoing, U.S. Pat. No. 4,965,738 discloses that sensors, which detect the magnitude of an electric current flowing in a battery and the temperature of the battery, are provided in a battery pack and that a microprocessor is provided which outputs electric current and temperature data in accordance with a request from a battery charger corresponding to the above-described portable computer. In a charge controller of the battery charger, a charge-start time and a charge-stop time are determined on the basis of inputted electric current data, temperature data, or the like.
However, in the above-described charge controlling system, for example, when the battery pack is replaced by another one, the remaining capacity of the newly inserted battery pack cannot be detected because data concerning this new battery pack has not been accumulated in the charge controller. Another drawback exists such that in cases when a power source of the portable computer is turned off and when an AC adapter is disconnected from the portable computer, data concerning the battery pack is lost unless a backup of the memory which stores data concerning the battery pack in the charge controller is effected. For this reason replacement of a battery pack, power-on of a computer, connection of an AC/DC adapter, or the like is conventionally utilized as a trigger, so as to automatically start charging for a battery pack. Thus, even when a battery pack is replaced for another battery pack, charging for the newly inserted battery pack is effected, thereby overcharging the newly inserted battery pack.
Further, the criteria for judging whether or not a battery main body in the battery pack has been brought into a full-charged state, i.e., whether or not charging for the battery pack has been completed, vary according to the manufacturer of the battery pack, the kind of cell used in the battery main body, the capacity of the battery pack, and the like. In relation to the above-described charge control, the charge controller cannot detect the criteria for judging whether or not charging for the installed battery pack has been finished. Accordingly, there exists a drawback in that, when a battery pack, having criteria different from those of a standard battery pack which were set when a portable computer was designed, is installed in the portable computer, charging for this installed battery pack cannot be stopped at the suitable time.